Flow control means for multi-stage flash evaporators



1967 R. w. GOELDNER 3,336,966

FLOW CONTROL MEANS FOR MULTl-STAGE FLASH EVAPORATORS Filed June 22, 1965 g (31% ix 22 [ml/anion Richard Z1 Goeidnev United States Patent 3,336,966 FLOW CONTROL MEANS FOR MULTI-STAGE FLASH EVAPORATORS Richard W. Goeldner, Brookfield, Wis., assignor to Aqua-Chem, Inc., a corporation of Wisconsin Filed June 22, 1965, Ser. No. 466,044 7 Claims. (Cl. 159-2) This invention relates in general to flash evaporators, and more particularly to an improved multi-stage flash evaporator wherein means are provided to effect a positive vapor seal between adjacent stages of the flash evaporator.

In the flash evaporator art it has been proposed to divide an enclosure into a plurality of flash chambers by a plurality of spaced partitions extending transversely across the enclosure. The partitions have usually each included passage means therein so that sea water and the like can be conveyed successively through each of the flash chambers. Each of the downstream flash chambers has been maintained at a lower pressure than its adjacent upstream flash chamber so that a predetermined amount of the liquid flowing through the flash evaporator is flashed in each of the chambers. Such flash evaporators are typified by that disclosed in the copending application of Reid Ewing, Ser. No. 779,516, now US. Patent No. 3,213,000, entitled Evaporator and having the same assignee as the present application. Reference may be made to the Ewing application for a more complete description of the flash evaporator.

In large plants, which often operate under varying loads, the quantity of liquid flowing through the evaporator varies. Because of the pressure diflerences in adjacent flash chambers, difficulty has been encountered in the past in providing an effective vapor seal between adjacent flash chambers for all loads under which the evaporator is operated.

Accordingly, the general purpose of the present invention is to provide a flash evaporator of the character described, which includes effective means for sealing adjacent flash chambers regardless of the quantity of liquid flowing through the flash evaporator.

An object of the invention is to provide float operated sealing means in association with the partitions of a multistage flash evaporator to provide an effective seal between the upper surface of the liquid flowing through the evaporator and the passages in the partitions.

Another object of the invention is to provide a movable gate on each of the partitions of a multi-stage flash evaporator adjacent the passages therein, which is operatively responsive to the level of liquid flowing through the flash evaporator, so as to provide an effective seal between the upper level of the liquid and the passages in the partitions. A further object of the invention is to provide a flash evaporator as described above wherein the movable gates are closely confined within the interior of the flash evaporator.

Still another object of the invention is to provide a flash evaporator as' described above with novel linkage means for controlling movement of the gates.

A still further object of the invention is to provide a flash evaporator as described above with guide means for controlling the movement of the gates in response to changes in the level of liquid flowing through the flash evaporator. I

vThese and other objects of the invention will hereinafter become more fully apparent from the following description, taken in connection with the annexed drawing, wherein:

' age means 26 operatively responsive FIG. 1 is a diagrammatic showing of a multi-stage flash evaporator;

FIG. 2 is a fragmentary diametric section of a tubular flash evaporator provided with the vapor sealing means embodying the invention;

FIG. 3 is a sectional view taken generally along line 3-3 of FIG. 2;

FIG. 4 is a diametric section similar to that of FIG. 1, and illustrating a modified form of the invention; and

FIG. 5 is a diametric section similar to that of FIG. 1, and illustrating a further modified form of the invention.

While this invention is susceptible of embodiment in many different forms, there is shown in the drawing and will herein be described in detail an embodiment of the invention together with modifications thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiments illustrated. The scope of the invention will be pointed out in the appended claims.

In the exemplary embodiment of the invention as disclosed in FIGS. 1, 2 and 3 of the drawing, a flash evaporator structure generally designated 10 is shown to comprise an enclosure, herein a horizontally extending tubular shell 11, and having a plurality of upright walls or partitions 12 extending transversely across the shell and dividing the interior thereof into a plurality of flash chambers. Two such flash chambers are shown at 13 and 14 in FIGS. 1 and 2 and will hereinafter be described in detail. The lower end 15 of the wall 12 between chambers 13 and 14 is spaced above the bottom 16 of the shell to define therewith a passage 17 for flow of liquid such as sea water 18 from chamber 13 to chamber 14. As illustrated schematically in FIG. 1, liquid 18 may be passed through the evaporator 10 by means of a pump P from a supply inlet 20, the brine being passed from the evaporator through an outlet 21, and the distillate being delivered from the evaporator through an outlet 22. Each of the chambers is provided with means 23 for connecting the chambers to suitable evacuating means, it being understood that the pressure and temperature gradually decreases from the upstream chambers to the downstream chambers.

The quantity of liquid 18 flowing through the evapora tor 10 will vary, depending upon the magnitude of the load being serviced. Since adjacentflash chambers, such as 13 and 14, are at different pressures, a positive seal must be provided between the lower end 15 of the wall 12 and the upper surface of the liquid 18 to prevent flashing liquid from escaping from one stage of the evaporator to an adjacent evaporator stage. In the embodiment illustrated in FIGS. 1-3, a movable gate 24 is pivotally secured to the lower end 15 of the wall 12 as at 25. As can be best seen in FIG. 3, the outer ends of the gate 24 are arcuately shaped, so as to fit sufficiently closely within the interior of shell 11 to create an effective vapor seal between the upper surface of the liquid 18 and the lower end 15 of the wall 12.

Means are provided for operating gate 24 which are responsive to the level of liquid 18 flowing through the evaporator, and include linkage means shown generally at 26 in FIG. 2. An arm 27 is fixed on gate 24 adjacent the mid-portion thereof, and extends rearwardly and upwardly therefrom. Linkage means 26 includes a first generally vertically extending link 28 having its lower end pivotally connected to the upper end of arm 27 at 29. Linkage means 26 further includes a second generally vertically extending link 30, which carries a suitable float member 31 at the lower end thereof. Float member 31 is adapted to float on the upper surface of the liquid 18 flowing through the evaporator, so as to render the link-. to the level of liquid flowing through the evaporator. The linkage means 26 further includes a generally horizontally extending link 32 pivotally secured at one end 33 to the upper end of link 28, and pivotally secured at the other end 34 to the upper end of link 30. Link 32 is mounted for pivotal movement about the mid-portion thereof by a transverse pivot member 35 provided in the shell 11. Thus, it will be readily understood that as the level of liquid in the shell 11 rises, link 32 will be pivoted in a clockwise direction as viewed in FIG. 2, to move link 28 downwardly and retain the gate 24 in effective sealing engagement with the upper surface of the liquid 18 flowing through the evaporator. When the level of liquid 18 is lowered, the link 32 will be pivoted in a counterclockwise direction as viewed in FIG. 2, to move the link 28 upwardly and cause the gate 24 to move downwardly into effective sealing engagement with the upper surface of the liquid 18. Thus, it will be readily appreciated that the movable gate 24, and the float operated linkage means cooperate to provide an effective seal which is operatively responsive to the level of liquid flowing through the evaporator, and which provides an effective seal between chombers 13 and 14 regardless of the level of liquid flowing through the evaporator.

Turning now to the embodiment illustrated in FIG. 4, a flash evaporator 110 is shown to include a shell 111 having a wall or partition 112 extending transversely across the interior thereof and dividing the shell into adjacent flash chambers 113 and 114. Means 119 are provided for effecting a positive seal between the lower end 115 of the Wall 112, and the upper level of the liquid 118 flowing through the passage 117 defined between the lower end 115 of the wall 112 and the bottom 116 of the shell 111.

The sealing means 119 includes a floating gate member 120 which is responsive to the level of the liquid 118 flowing through the evaporator, and which is adapted to float upon the upper surface thereof. The floating gate member 120 includes a pair of spaced parallel sides 121 and 122, and side 121 is positioned in sliding face abutting engagement with the wall 115. Guide means 123 are provided to control the movement of gate 120, and the guide means 123 are preferably secured to the wall 112 and to the interior of the shell 111. The guide means 123 includes wall portions 124 on opposite sides of the shell 111, and as is clear from FIG. 4, wall portions 124 are spaced from and parallel with the wall 112. The side 122 of the gate 120 is positioned in sliding face abutting engagement with the wall portions 124, so that the wall 112 and the wall portions 124 cooperate to eflectively guide the gate 120 in its vertical movement. It will be understood, of course, that the outer ends of the gate 120 are shaped similarly to the outer ends of the gate 24 shown in FIG. 3, so that the gate 120 will provide an effective vapor seal between chambers 113 and 114. The gate member 120 is preferably hollow in construction so as to be sufliciently buoyant to float upon the upper surface of the liquid 118.

In the embodiment illustrated in FIG. 5, a flash evaporator 210 includes an enclosure 211 that is provided with a wall or partition 212 extending across the interior thereof to divide the interior into adjacent flash chambers 213 and 214. The lower portion 215 of wall 212 is spaced from the lower portion 216 of the shell 211 to define a passage 217 therebetween through which the liquid 218 flows. A movable gate 219 is pivotally secured to the lower end 215 of wall 212 at 220, and a float member 221 is formed integrally with the movable gate 219. The float member 221 is preferably hollow in construction so as to be sufficiently buoyant to make the gate 219 operatively responsive to the level of liquid 218 flowing through the evaporator 210.

From the foregoing it will be readily appreciated that applicant has provided novel movable gate means which are operatively responsive to the level of liquid flowing through the flash evaporator so as to provide an eflective seal between adjacent stages of the evaporator. The present invention contemplates that suitable condensing means (not shown will be provided in association with each flash chamber to condense the flashed vapors. In a preferred embodiment, cooling brine may be pumped through the evaporator in a first direction to condense the flashed vapors, and may be recirculated through the evaporator in an opposite direction (after heating thereof) for flashing purposes. From the above, it will be appreciated that each of the objects of the invention has been fully achieved.

I claim:

1. In a flash evaporator, a generally horizontally extending enclosure, a generally upright wall extending transversely across the enclosure dividing the interior thereof into a pair of flash chambers; said wall defining a passage at the lower end thereof for flow of liquid from one chamber to the other chamber; pump means for maintaining a flow of liquid to be evaporated successively through said one chamber, said passage, and said other chamber; means for maintaining a lower pressure in said other chamber than in said one chamber; and means movably mounted on said wall and operatively responsive to the level of liquid adjacent said wall for providing an effective seal between the lower end of the wall and the upper surface of the liquid, said last named means including a gate valve means having at least a first surface thereof exposed to said lower pressure in said other chamber and a second surface thereof exposed to the one chamber, inclined downwardly away from the one chamber and positioned to receive an upward component of force by the flow of liquid therepast, so that the rise and fall of the gate valve means is in phase with the rise and fall of liquid level in said one chamber.

2. A flash evaporator as defined in claim 1 wherein said gate valve means is pivotally mounted on said wall adjacent the lower end thereof and has float means thereon engaging said liquid.

3. A flash evaporator as defined in claim 1 wherein said gate valve means is pivotally mounted adjacent the lower end of said wall and extends downwardly therefrom into position for engagement with the upper surface of said liquid, and said gate valve means further includes float means responsive to the level of liquid in said one chamber, and linkage means connects said float means and said gate for retaining said gate in sealing engagement with the upper surface of liquid in said enclosure.

4. A flash evaporator as defined in claim 3 wherein an arm is fixed on said gate valve means; and said linkage means includes a generally vertically extending first link pivotally connected to said arm, a generally vertically extending second link connected to said float, and a generally horizontally disposed third link pivotally mounted in said enclosure adjacent the mid-portion thereof and having one of its outer ends pivotally secured to the upper end of said first link and the other of its outer ends pivotally secured to the upper end of the second link.

5. A flash evaporator as defined in claim 1 wherein guide means are provided on said wall adjacent the lower end thereof, and said gate valve means is confined within said guide means and floats upon said liquid.

6. A flash evaporator as defined in claim 5 wherein said guide means includes a further wall in said enclosure spaced from and parallel with said first mentioned wall, and said gate valve means is defined by a gate member that is provided with spaced parallel sides each slidably engaging one of said walls.

7. In a multi-stage flash evaporator having a downstream flash chamber at a lower pressure than an adjacent upstream flash chamber and separated therefrom by a partition with a passage therein, the improvement comprising: pump means for maintaining a flow of liquid to be evaporated through said upstream chamber, said passage, and said downstream chamber; and self-adjusting sealing means associated with said partition and operatively responsive to the level of liquid adjacent said passage to effectively seal said passage even though the level of liquid adjacent said passage is below the lower edge of said partition, said last named means including a gate valve means having at least a first surface thereof exposed to said lower pressure in said downstream chamher and a second surface thereof positioned to receive an upward component of force by the flow of liquid therepast, so that the rise and fall of the gate valve means is in phase with the rise and fall of liquid level in said upstream chamber.

References Cited UNITED STATES PATENTS Elliott 202-173 Lockrnan 922 Mulford 202-173 Kingma 1592 Woodward 202-173 10 NORMAN YUDKOFF, Primary Examiner.

J. SOFER, Assistant Examiner. 

1. IN A FLASH EVAPORATOR, A GENERALLY HORIZONTALLY EXTENDING ENCLOSURE, A GENERALLY UPRIGHT WALL EXTENDING TRANSVERSELY ACROSS THE ENCLOSURE DIVIDING THE INTERIOR THEREOF INTO A PAIR OF FLASH CHAMBERS; SAID WALL DEFINING A PASSAGE AT THE LOWER END THEREOF FOR FLOW OF LIQUID FROM ONE CHAMBER TO THE OTHER CHAMBER; PUMP MEANS FOR MAINTAINING A FLOW OF LIQUID TO BE EVAPORATED SUCCESSIVELY THROUGH SAID ONE CHAMBER, SAID PASSAGE AND SAID OTHER CHAMBER; MEANS FOR MAINTAINING A LOWER PRESSURE IN SAID OTHER CHAMBER THAN IN SAID ONE CHAMBER; AND MEANS MOVABLY MOUNTED ON SAID WALL AND OPERATIVELY RESPONSIVE TO THE LEVEL OF LIQUID ADJACENT SAID WALL FOR PROVIDING AN EFFECTIVE SEAL BETWEEN THE LOWER END OF THE WALL AND THE UPPER SURFACE OF THE LIQUID, SAID LAST NAMED MEANS INCLUDING A GATE VALVE MEANS HAVING AT LEAST A FIRST SURFACE THEREOF EXPOSED TO SAID LOWER PRESSURE IN SAID OTHER CHAMBER AND A SECOND SURFACE THEREOF EXPOSED TO THE ONE CHAMBER, INCLINED DOWNWARDLY AWAY FROM THE ONE CHAMBER AND POSITIONED TO RECEIVE AN UPWARD COMPONENT OF FORCE BY THE FLOW OF LIQUID THEREPAST, SO THAT THE RISE AND FALL OF THE GATE VALVE MEANS IS IN PHASE WITH THE RISE AND FALL OF LIQUID LEVEL IN SAID ONE CHAMBER. 